You must be responsible for what you do
must be 一定；一定要；肯定是
must be 通常表示推测,此时的must表示“一定”
如：There must be a mistake. 一定是弄错了.
must be 有时也不一定表示推测,而是表示“必须”
You must be working when the inspector comes in.
检查员进来时你必须在工作.
You must be responsible for what you do
must be 一定；一定要；肯定是
must be 通常表示推测,此时的must表示“一定”
如：There must be a mistake. 一定是弄错了.
must be 有时也不一定表示推测,而是表示“必须”
You must be working when the inspector comes in.
检查员进来时你必须在工作.